The present invention relates to intra-body anchoring mechanisms and, in particular, it concerns anchoring mechanisms and methods for anchoring a device at a desired angle relative to a biological conduit, and associated applications of such mechanisms in devices and methods.
One aspect of this invention deals with drug delivery. There are treatments for lung diseases for which the continuing application of drugs is required. One example is the treatment for destroying lung lesions. Although the drug is applied in a systemic manner to the entire body, it is concentrated inside cells having high metabolic activity. Beyond a certain level of concentration, the cell is destroyed. Cancerous cells, which are the target of such drugs, have such high metabolic activity. However there are additional body organs that attract the drug to concentrate in them. As a consequence, besides destroying the lesion, the drug also has a strong side effect of poisoning other organs in the body. There is an advantage to giving the medicine in high doses directly to the infected lung area either as a supplement or as a replacement to the traditional treatment.
Hence, there is an advantage of having a method and apparatus to apply a medicine or plurality of medicines directly to a certain location inside the lung, and furthermore to doing it continuously according to the required delivery profile.
FIG. 1 is a general description of the concentration of a drug in the patient's blood when the drug is given in doses. Every time the dose is given, the concentration is increased sharply and then decays over time. However the drug has the desired therapeutic effect only when its concentration in the blood is higher than a % and lower than b %, where a and b are individuals to the nature of the specific drug and patient condition. When the concentration is lower than a %, the drug is not sufficiently effective. When the concentration is higher than b %, the concentration is so high that it is likely to cause damage to the patient.
Therefore, it is preferred to give the drug constantly in order to keep its concentration within the patient's blood within the desired range. Devices for slow release or delayed release of drugs are well known in the art. An example is U.S. Pat. No. 3,760,984 to Theeuwes titled “Osmotically Powered Agent Dispensing Device With Filling Means”, which is fully incorporated here by its reference. It describes a dual chamber capsule, with one chamber internal to the other. The internal chamber is formed of contractible foil and contains the drug to be delivered. The external chamber contains an osmotic solution. The outer layer is formed of a substance that is permeable to external fluid and impermeable to the internal solute. The osmotic pressure developed in the outer chamber contracts the internal layer and pushes the drug through an orifice.
The outer shape of the prior art devices is pre-shaped to the volume needed for containing the drug and the osmotic solution. Therefore they are not suitable for being delivered through the working channel of a bronchoscope which, for those in regular use by bronchoscopists, is less than 1.8 mm in diameter. Therefore it would be of benefit to have a drug delivery device that is sufficiently flexible and thin to be inserted through the working channel of the bronchoscope and can be directed through the pulmonary tree to a desired destination in the periphery of the lung, where the width of the bronchial airways is as small as 1 to 2 mm. It would also be of benefit to have a container for the drug which holds enough volume for long-term treatment and yet is able to pass through a sheath fine enough to enter airways of the aforementioned dimensions. It would also be of benefit to have an anchoring mechanism for securing the position of the device, once inserted, at its designated location for the duration of the treatment, while allowing its release and withdrawal after the treatment is done.
Brachytherapy or Seed implant is a technique of radiotherapy in which small seeds of radioactive materials implanted adjacent to the cancerous lesion. In the lung, this procedure is performed by inserting a thin flexible catheter via the working channel of the bronchoscope, into the designated lung airway, which is left there during the entire emission of the radiation. Since it is extremely inconvenient to remain for a long period of time with this catheter inserted through the bronchus, seeds emitting high dose radiation are often used to shorten the exposure time. This high-dose emission has the undesirable side effect of causing bleeding. On the other hand, using seeds of lower emission prolongs the treatment, which is undesirable too.
Often drugs are given to the patient as part of this treatment such as antibiotics and pain relief. Hence, in certain conditions it might be of benefit to incorporate brachytherapy in conjunction with said drug delivery device.
Another aspect of the invention is the need for a directional anchoring mechanism when performing a pulmonary needle biopsy and other similar procedures.
Currently, needle biopsy is performed through the working channel of the bronchoscope. First, the bronchoscope is guided through the pulmonary tree to the location where the biopsy has to be taken. Then, a flexible catheter having a biopsy needle at its distal tip is inserted through the working channel and punctured through the wall of the pulmonary passageway to the center of the lesion. This procedure is often dangerous because vital organs such as big blood vessels can be damaged if the needle mistakenly hits them. Guiding the needle according to 3 dimensional (3D) imaging data such as Computer Tomography (CT) data may avoid such damage.
PCT application WO 03/086498 to Gilboa, titled “Endoscopic Structures and Techniques for Navigating to a Target in Branched Structure”, fully incorporated here by reference, describes methods and apparatus for navigating and leading bronchoscopic tools to the periphery of the lung in context of CT data. A steerable locatable guide, having a location sensor and a deflection mechanism incorporated at its distal tip, is inserted encompassed in a sheath and is used to navigate and place the distal tip of that encompassing sheath at a designated target location inside the lung.
This sheath is subsequently used effectively as an extension to the working channel of the bronchoscope to the periphery of the lung, where the bronchoscope itself cannot reach because of its thickness. First, registration between the CT data and the body of the patient is performed. Then, the locatable guide can be navigated through the branches of the pulmonary tree using the measured location coordinates of the guide's tip overlaid on the CT images. After bringing the tip to the target, the guide is withdrawn and a bronchoscopic tool is inserting into the empty sheath and pushed through it up to the target.
This method and apparatus may be used for bringing a biopsy needle to the target. The sheath has to have a diameter that is sufficiently large to allow insertion of tools through it, and yet sufficiently small for itself being inserted through the working channel of the bronchoscope. Therefore there is insufficient room for incorporating a steering mechanism as part of the sheath itself, and navigation should rely on the steering mechanism of the guide. When the tip is at the target, the guide has to be deflected in order to direct the end portion of the sheath toward the lesion, which is usually located at the side of the passageway. As a consequence, when the guide is withdrawn, the tip of the sheath loses its support, and might not be pointing to the direction of the target anymore. Hence it would be of benefit to have an anchoring mechanism for holding the tip of the sheath correctly oriented (angled) in the direction of the target, even when the guide with its steerable mechanism is withdrawn.